Electric switch



Feb. 20, 1934. M. RussELL `1=:r AL

ELECTRIC SWITCH Filed June 6, 1932 2 Sheets--SheerI l Feb. zo, 1934. M; N. RUSSELL mm. -1,a48,399

ELECTRIC SWITCH i Filed June 6, 1932 2 Sheets-Sheet 2 [Mg /zf vso Patented' Feb, zo, 1934 PATENT OFFICE ELECTRIC SWITCH Mark N. Russell and Victor B. Despard, Syracuse,

N. Y., assignors to Pass & Seymour, Inc., Syracuse, N. Y., a corporation of New York Application June 6, 1932. Serial No. 615,675 v 13 claims. (c1. zoo-67) This invention relates to electrical switches, and particularly to switches of the snap type for use in the wiring of buildings for light, and for power, and for portable devices.

It is a general object of the present invention to provide novel and improved switches of the type described.

More particularly it is an object of the invention to provide a series of snap switches in which the housing, stationary contacts and operating mechanism are substantially identical in each of the series and wherein the type of switch can .be changed by the changing of a bridging contact carrier.

An important feature of the invention resides in the manner of mounting the switch operating mechanism in the housing or shell wherein it has but a single point of support and one or more supports on the cover closing the rear of the shell.

Another important feature of the invention resides in the manner of mounting and retaining the contacts and their terminal plates in position in the housing.

A further important feature of the invention resides in the novel, positive kick-off means used inthe switch operating mechanism to ensure initiation of movement of the bridging contact carrier near the beginning of the movement of the operating handle. A further novel feature resides in the arrangement of the contacts and.v terminal plates for switches of the double pole, three-way and four- Way types and in the cooperation therewith of the bridging contacts movable by the switch operating mechanism.

Other and further features and objects of the invention will be more apparent to those skilled in this art upon a consideration of the accompanying drawings and following specification wherein are disclosed several exemplary embodiments of the invention with the understanding that such changes, modifications and variations may be made therein as properly fall within the scope of the appended claims without departing from the spirit thereof.

In said drawings:

Figure 1 is a side elevation of a single pole switch constructed according to the present invention and showing one side of the shell broken away to permit a view of the interior;

Figure 2 is a rear view showing the cover plate and its fastening means removed;

Figure 3 is a section on line 3-3 of Figure 2;

Figure 4 is a section on line 4 4 of Figure 3;

Figure 5 is a fragmentary view showing the operating handle moved through one half of its arc from the positions of Figures 1 and 3 to show the cooperation of the kick-off lugs;

Figure 6 is a fragmentary section on line 6-6 6o of Figure V1 showing the forward mounting of the switch frame in the shell;

Figure 'I is a view similar to Figure 1 but showing a double pole switch;

Figure 8 is a face view of the. movable contact 65 bridging member assembly; i

Figure 9 is an edge view of the movable contact assembly of Figure 8;

Figure 10 is a view similar to Figure 8 show-p l ing the movable contact assembly adapted for 7o use in the same shell as Figure '7 but to provide ,a three-way switch;

Figure 11 is a schematic view showing the four terminals of the three-way switch together with the bridging member contacts in one position; l

Figure 12 is a view similar to Figure 11 showing the bridging member contacts in another position; l

Figure 13 is a view similar to Figures 8 and 10 so but showing the movable contact assembly equipped to make a four-way switch on use with the casing and contacts shown in Figure 1;

Figure 14 is a fragmentary section on line 14-14 of Figure 13 showing one bridging mema5 ber contact extending through the carrier:

Figure 15 is a view similar to Figure 11 showing the relation of the stationary contacts and bridging member contacts for one setting of the four-way switch; and

Figure 16 is a similar view showing the position of the stationary contacts and bridging member contacts for the other setting of the four-way switch.

The present invention is particularly directed to snap switches of the type used in the walls of houses and buildings, `usually for' controlling lights, and is of the so-called toggle or tumbler type adapted to act with a snap to ensure against burning or arcing of the contacts. The construction, while particularly adapted for this use and primarily intended for switches of very small size, is not necessarily so limited and'may be applied to other constructions where the novel features will be beneficial.

The switches disclosed in the drawings are of a type for use in the interchangeable line of wiring devices as disclosed in Patent No. 1,875,224 granted to Victor R. Despard August 30, 1932, for Electrical wiring apparatus, and are intended to be mounted in a suitable bridge as disclosed in that application. Their compact size is necessary since they can be mounted three to a single gang outlet box or in combination with two other wiring devices in such a box.

In accordance with the showing in the patent referred to above, it will be appreciated that the switches must be of such size that their maximum overall length is less than the width defined in that patent of a single gang box or aperture. Since the switches because of their being used in stacks or groups must be wired on their ends, it is evident that their overall length must be somewhat less than gang width in order to provide thickness for wires between the ends of the switches and the box walls where a single gang box is used. Because of the use of the switches in groups of as many as three per gang, the minimum wi th or thickness of a switch must be somewhat less than one-third of the'length of a single gang or gang opening. It is obvious then that the maximum space requirements of a switch is best fulfilled by the use of a casing substantially rectangular in cross section and it is the intent of the invention to best utilize the very limited space permitted by the limitations dened above to produce a switch of maximum ruggedness and low cost.

The invention is particularly directed to a series of switches whereby various types (as regards function) can be made with a single type of shell and a single arrangement of stationary contacts and terminal plates, the only difference in the types being in the number of bridging contact members carried on the bridging carrier which is moved by the form of operating mechanism common to all of the switches. For the double pole switch a pair of bridging member contacts is used. To'convert this into a three-way switch one additional bridging member contact is applied, and to further convert this into a four-way switch still another bridging member contact is added. While a single pole switch could be constructed from this same arrangement, it is found convenient to slightly vary the construction in the case of a single pole type to "provide the more rugged device in which the circuit is made or broken at four independent places to ensure long life and freedom from destructive arcing, burning andA roughening of the contacts.

Referring now to the drawings and rst to the rst sheet thereof which is directed entirely to the single vpole switch, there is shown at 20 a shell, casing or housing preferably molded from insulating material such as one of the condensation products. Its shape in cross section is substantially rectangularI as seen in Figure 2 The front end 21 is smaller than the main cross section in order to be received in the bridge previously referred to, for which purpose it has a shoulder 22. A further shoulder 23 provides a neck for passage through the wall plate. This neck is hollow as at 24 to pass the operating handle 25, when the switch mechanism is assembled into the shell through the open rear end 26 thereof.

Each of the side walls 27 and 28 of the shell is provided with a pair of grooves, 29, 29 and 30, 30 respectively, closely adjacent to the end walls 31 of the shell and extending from the open rear toward the front of the shell. The grooves 29 are closer together than the grooves 30 as seen in Figure 2. Each pair of grooves, one 29 and one 30, is adapted to receive and retain a terminal plate 33 which is a heavy plate of sheet metal of a width to reach just to the bottom shoulders 34 of the grooves when the upper edge 35 thereof is flush with the rear end of the shell. 'I'he plate has a central offset 36 so that its terminal screw receivingportion is closer in toward the center of the shell than is the contact spring receiving portion. Each plate is equipped with a terminal screw 38 threaded therein and adapted to clamp a wire beneath its head and against the outer face of the terminal plate. For thc purpose of giving access to these screws, the end walls 31 of the shell are cut away as at 40 in substantially U-shaped notches extending forwardly from the rear edge to leave plenty of room to manipulate the wire beneath the screw heads.

Projecting inwardly and forwardly into the housing from the opposite end of each of the terminal plates is a contact spring 42 having two spaced arms 43 and 44 united by an integral base 45 appropriately attached in a rigid manner to the inner face of the terminal plate. At the sides of their ends, the arms 43 and 44 are provided with the lateral wings 46, each turning outwardly or away from its companion spring. There are thus formed at the ends of the two arms, the active contacting parts of the contact springs with the guide wings at their sides.

For cooperation with these springs to close the circuit between those connected to one terminal plate and those connected to the other, there is the bridging member carrier or disc mounted for operation as will be subsequently described, so that it is oscillated about a center, indicated by the reference character 51 concentric to its edge 52. The disc is not a full circle but is cut away as shown forwardly of the center so that it will be properly accommodated in the small housing.

Against one face of the disc 50 which is formed of a sheet of suitable insulating material is the bridging member or strap 53 having the active ends 54 arranged inwardly from the edge of the disc on an arc which passes through the centers of the active faces of the contact springs. These springs bear firmly on the two faces of the disc. Adjacent the faces 54 the disc is slotted as at 55 and wings which extend from the radial edges of the parts 54 pass through the disc and are folded over on the back thereof to serve not only to mechanically connect the bridging member to the disc but to provide on the far side electrical connections to engage the contact spring arms 43, and through the intermediate strap portion on the front face to connect them together electrically.

Thedisc is shown in Figure l positioned off with one bridging member tip 54 intermediate the spring contacts and the other beyond one of them. When rotated an arcuate distance equal to that between the intermediate tip and the right hand contact spring the switch is on, and it will be seen that there are four points of make and break for the circuit, two at each contact spring.

The operating mechanism for the switch is of the snap type and is carried by a frame 60 substantially U-shape in plan as seen in Figure 2 and comprising spaced parallel plates 6l and 62. The plate 61 has an offset end 63, best seen in Figure 6, which is tapered as seen in Figure l and fits within a correspondingly tapered notch 64 in the front end 21 of the shell to support and center the frame therein. This is the only point of contact of the frame with the shell.

contact carrier operator pivots.

switch housing. This cover is held on by having applied over it the metal plate 69 having the turned-down ears 70 received in notches`71 in `the outer sides of the side walls of the housing and vexpanded thereinor otherwise attached thereto. Appropriate holes 73 in the metal plate clear the lugs 66 so that the frame is insulated from this metal plate. A slight resiliency in the insulation cover and the metal plate causes a pressure on the rear end of the frame plate 61 to push the lug 63 into the tapered recess 64 and ensure rigid three-point mounting for the switch operating mechanism.

Near the forward end of the frame plates there is a pivot pin 75 extending between them and forming the fulcrum for the switch operating lever 76 formed of a metal strap having secured thereto the -insulated handle 25 which projects through the aperture 24 on the front of the shell for manipulating the switch.

As seen in Figure 5, the plates forming the sides of the frame are cut away toprovide the sector-like openings 78 and the smaller openings 78 between which project the hooks 79 opening toward the pivot pin 75. Hanging on these hooks, which form the fulcrums therefor, is .the bridging member carrier operator 80, generally of U-shape form having the arms 81 and 82 connected by the cross strap 83'which swings in the openings 78 and is stopped by the ends thereof to limit its movement. It vhas inwardly projecting lugs 84 from near the tops of the arms 81 and 82 which are received in the hooks 79 and their edges form the center about which this member oscillates. It is held in the hooks and given its movement by means of a coil spring 85 connected between the cross member 83 and the lower end 86 of the operating lever, which end and spring work between the arms 81 and 82 of the contact operator.

The operation of this assembly to produce a snap action will be appreciated by. those skilled in the art. the spring holds the cross arm 83 oppositely disposed to the end 86 of the operating lever which also stops against one or the other of the ends of the openings 78 in the frame plates. As the operating handle is swung to the opposite extreme, the spring passes over its dead center and forces the contact carrier operator to move until its cross arm 83 engages the opposite side of the recesses in the frame plates.

To ensure movement of the contact carrier operator in spite of any sticking of the contacts and so as not to place too much relianceon the spring, a positive kick-01T mechanism is applied. This includes a lug 90 extending upwardly and inwardly from the arm 82 of the contact carrier operator so that it projects between the frame plates and is positioned between the pivot 75 for the operating lever and the hooks 79 forming the It extends between a pair of spaced kick-off lugs each extending rst laterally from the operating lever and then bent up at right angles thereto, so that their ends extend in a direction parallel to the pivot of this lever.

When in the position of Figure 3,l

operating handle positively forces this' lug 90 toward the left as the switch handle moves toward the right and since the lug 90 is on the opposite side of the pivot 84 of the contact carrier operator from the cross .arm 83, it will be seen that the cross arm will be forced toward the right, which action will be then augmented by the spring which continues and completes the snap action. For reverse movement, a similar action takes place. v

The upward continuation of the arm 82 of the contact carrier operator extends on beyond the lug 90 and outside of the frame member 62 to provide the driving lug 94 which extends loosely through slot 95 in the bridging contact carrier disc 50. No attaching means is necessary, for the disc is held rigidly inits plane by the clasp of the four straddling contact springs and can be said to float between these springs, beinggiven its oscillating movement by the snap mechanism just described. j

The assembly of the switch is very simple,I for the disc is applied tothe driving lug on the operating mechanism assembly and the whole dropped into position, so that the lug 63 drops into the notch 64. The terminal plates'are then positioned into their slots in the sides, with the walls of which they have a tight fit, so that the contact springs straddle the carrier disc. The insulation cover plate is then applied with its holes fitting over the lugs on the operating mechanism frame plate and the metal cover plate applied and fastened.` The insulation cover plate is not only instrumental in maintaining the operating mechanisrn frame rigidly in position but it holds the terminal plates tightly against thebottoms of their grooves and ensures their rigidity in the whole assembly.

The modifications shown on the second sheet of drawings are for switches other than of the single pole type. Their construction is substantially the same in major details as the single pole switch although the shell is of slightly different exterior conlguration in order to accommodate the two additional terminal plates. There are four terminal plates, two at each end, the upper ones being numbered 101 and the lower ones 102. They flt in the same .types of grooves as those explained in connection with the single pole switch but `the grooves are more than twice as deep, reaching clear to the shoulders 103 near the front of the shell. In assembly, the forward terminal plates 102 are rst put in position, then small insulating members 104 are slid into the grooves over them to space them from the rear terminal plates 101 which are last positioned. The cover plates are assembled asin thev first disclosed embodiment.

The operating mechanism is identical and is positioned the same as in the single pole switch. and there is a bridging contact carrier disc 105 mounted on the driving lug of the operating mechanism in exactly the same manner by having its slot 106 passed over that lug.

Each terminal plate is provided with but au single contact spring instead of the double one which engages bothA sides of the carrier. In Figure 7, the terminal plates 101 have the forwardly and inwardly facing springs 107 having similar functioning ends to the springs describedin connection with the rst embodiment. These'springs pass on the inner side of the carrier disc 105.

The forward terminal plates 102 are equipped each with a, single spring 108, which springs pass rearwardly and inwardly and have their func-` tioning ends engaging the outer face of the carrier plate. 'I'he functioning ends of bthe two springs of the pair of terminal plates, at either end of the shell, are confronting, and exert equal pressures on the two faces of the disc to maintain it in position the same as the twin contacts in the single pole type.

The switch shown in Figures 7, 8 and 9 is of the double pole type, i. e., breaks both sides of the circuit. In order that it may do this, it is provided with a contact bridging strap 110 on the outer face of the carrier disc and a second bridging member 111 on the inner face of the disc. The active ends 112 of the bridging member 110 are directly above the active ends 113 of the bridging member 111 so that in one position all of these active ends engage all of the active contact spring ends. In order that the two bridging straps may be insulated from each other, they are provided with non-overlapping portions 115, 116 on the bridging member 110 and 117, 118 on the bridging member 111, and through these portions the rivets are passed and headed over against the insulating material of the carrier disc.

In the position shown in Figure 7'the bridging straps are out of engagement with all of the contacts and the circuit is open. In the other position of the operating handle, the disc 105 is rotated to the right until the bridging straps thereon connect the contacts 107 together and the contacts 108 to each other and the circuits are completed. The terminal plates carry terminal screws exactly as shown in Figures 2 and 3 and suitable cut outs are provided for both in each end of the casing. In order that the shell be properly reinforced, there is a strip 120 between the forward and rear terminal screw apertures on each end, and, this requires that the forward terminal screw be inserted after that terminal strip is in position. l

The carrier disc 105 is duplicated in the one shown as 105 in Figure 10 in all respects and in addition is provided with a. loop 125 of conducting material which passes through the slotv 126 in the disc and around the edge 127 thereof and is pressed down as shown in Figure 14 to provide contact spring engaging faces 128, one on each side of the carrier disc and connected together. When such a disc is mounted in the shell and contact assembly of Figure 7, a so-called three-way switch is obtained. One of the contact springs is not used electrically but is retained in position to balance the pressure on the4 two sides of the carrier disc. The corresponding terminal screw may be omitted or a blank terminal plate used in its place.

Figures 11 and 12 are diagrammatic arrangements of the three-way switch showing the respective contact springs 107 on the upper side and 108 on the lower side entirely schematically. The bridging member carrier disc 105' is shown in Figure 11 positioned so that the .bridging strap 110 closes the circuit between the two contact springs 108 and the bridging strap 111 closes the circuit between the two springs 107. It the switch is now wired so that a single power line is connected to the right hand spring 107, current from this line may be conducted across the strap 111 and out of the other spring contact 107, forming one of the positions of the switch. The other bridging member 110 while engaging its two contacts is not used electrically in this arrangement.

When the switch is snapped to its other position, the two bridging straps are out of engagement with all of the springs, but the loop member 125 has now come into contact to close the circuit between the springs 107 and 108 at the right hand end, so that the power coming in through the spring 107 goes out through the spring 108, forming the second position of the switch. 'I'he use of two such switchesv in the so-called lazyma arrangement for lighting one light from two positions is well known.

If it is required to make a so-called fourway switch to be used, for instance, in connection with-two three-way switches to give Ya third position of control for a single light, then the arrangement shown in Figures 13, 15 and 16 may be used. Such a four-way switch is in effect a polarity reversing switch.

To provide a four-way switch, it is only necessary to take the contact carrier disc 105 and modify it as shown in Figure 13 at 1052 by the single addition of a second loop member 130 which is mounted in substantially the sameway as the member 125 by passing through two slots, 131, 132, in the disc about half way between the active ends of the main bridging straps. This member 130 extends on both sides of the disc exactly the same as the member 125 and is so positioned as to be active between the pair of contacts at the opposite end of the shell when the member 125 engages its pair of contacts.

Considering Figures l5 and 16, the operation of this type of switch will be clear. In Figure 15- the power is illustrated as coming in at the upper right hand terminal 107 and at the lower left hand terminal 108. Terminals of like numbering are connectedpto'gether by their bridging'straps 1102, 1112 andthe current goes out the opposite terminals of the same number from those where it entered as indicated by the arrows.

When the switch is moved so that the loops 125 and 130 cooperate with all of the terminals, then the conditions are as shown in Figure 16 with the current entering through the same terminals as before, but in this case leaving through terminals of a different number and at the same end of the switch. Thus current coming in at 107 on the right goes out at 108 on the right. If, for the sake of this description, we consider 107 on the right as plus and 108 on the left as minus, it will be seen in Figure 15 that 107 on the left is plus and 108 on the right is minus, 125

whereas in Figure 16, 107 .on the left is minus and 108 on the right is plus, just the reverse of Figure l5.

The great convenience and manufacturing simplicity of this switch will now be apparent, for

switches, as well as the terminals and contact springs. It is only necessary to add one or two'of the bridging loops to convert the switch of Figures 7 and 8`to that of Figure 10 or.13.

The lunique feature of this series of switches resides in the fact that the same terminals and contacts are used in every case and that the variations in function take place by slight changes in or additions to the movable member. In the conventional switches heretofore used for the same purpose, it was necessary to provide additional stationary contact members. In the conventional four-way switch there are eight stationary contact members connected to four `terminal members. Thus it is not possible in the old style switch to make any parts common, except the operating mechanism.

The arrangements described in connection with the second sheet of drawings enable a very cornpact assembly to be made and one that will readily ht into the very small contines permitted by the interchangeable line of devices disclosed 1n the Despard patent previously referred to. One of the unique features oi' the switches is that the arc occurring on the break is quickly smothered by the interposed non-conducting disc passing between the terminals so that the life o1 such switches is of great length.

Throughout the following claims the expression front end when referring to the switch casing or shell applies to that portion which substantially abuts the wall plate, back or rear refers to that portion most removed from the wall plate, sides or side walls refers to the longer walls extending from front to rear, and end or end walls refers to the shorter two walls extending from front to rear.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a snap' switch, in combination, a shell or insulating material having side walls, end walls, a front wall perforated for a switch operator, and an open back, a groove extending from the back toward the front in each side wall adjacent one end wall, a contact support member extending from groove to groove across the shell, a terminal carried by'said support, an opening in the adjacent end for access to said terminal, a switch mechanism having a frame in said shell and a 1 closure of insulating material for said rear opening, said closure engaging the contact support member and frame to hold them in the shell.

2. In a snap switch, in combination, a shell of insulating material having side walls, end walls, a front wall perforated for a switch operator, and an open back, a groove extending from the back toward the front in each side wall adjacent each end wall, a contact support member extendingv and a closure for said rear shell opening engaging said members and securing them in the grooves.

3. In a snap switch, in combination, a shell of insulating material open at its rear for the insertion of a switch mechanism, sides on said shell grooved longitudinally of the shell adjacent the ends of the shell, a pair of terminal plates extending adjacent eachshell end and having their ends in the grooves, insulating means separating the plates of each pair longitudinally of the grooves, and a closure for the rear opening of the shell engaging the rearmost terminal plate of each pair to hold the pairs in the shell.

4. In a snap switch, in combination, a shell of insulating material open at its rear for the insertion of a switch mechanism, sides on said shell grooved longitudinally of the shell adjacent the ends of the shell, a pair of terminal plates extending adjacent each shell end and having their ends in the grooves, insulating means separating the plates of each pair vlongitudinally of the grooves, and a contact spring on each terminal plate and extending toward the interior oi the shell, the active ends of the springs of a pair being overlying.

5. In a snap switch, in combination, a shell v of insulating material open at its rear for the insertion of a switch mechanism, sides on said shell grooved longitudinally of the shell adjacent the ends oi the shell, a pair of terminal plates extending adjacenty each shell end and having their ends in the grooves, insulating means separating the plates of each pair longitudinally of the grooves, a contact spring on each terminal pate and extending toward the interior of the Snell, the active ends of the springs of a pair being overlying, switch mechanism in said shell and including a plate of insulating material movable thereby and extending between said overlying ends o each pair of contacts, and Contact bridging members on said plate.

6, In a snap switch, in combination, an nsulating shell, means supporting two pairs of independent contact springs from -the ends of the shell with the active endsoi the springs of each pair facing each other, mechanism in said shell having a handle and a driving lug operable thereby, and an insulation plate adapted to be supported by said lug and t between the active ends of both pairs of contact springs; said plate being selected-from among a group of plates, one or said plates having bridging members thereon to form with the contact springs a double pole switch; another having bridging members thereon to form with three of the contact springs a three-way switch, and a third having bridging members to form with the contact springs a four-way switch.

7. In a switch in combination, an insulating base member, two pairs of independent contact springs carried thereby with the active ends of the springs of each pair substantially confronting each other, an operating mechanism adapted to be secured to said base and having a driving lug tiltable thereby, and a series of insulation members adapted to be singly and interchangeably mounted on said lug for tilting thereby and adapted to fit between the Contact springs of both pairs; each of said members having a pair of separate bridging elements thereon, each positioned to connect one contact of a pair with one of the other pair when the insulation member is in one position; one of said insulation members having an element to bridge the contacts of a pair when the member is in its other position; and another member having two elements to individually bridge the contacts of each pair when the member is in its other position.

8. In a snap switch, in combination, a shell of insulating material having, side walls, end walls, a front wall and an open back, grooves extending from the back toward theY front in each sidewall extending along each end wall and having its ends in two of said grooves, a Contact extending from the inner face of each plate, a terminal screw on the outer face of each plate, and each end wall having a suitable aperture for access to the screw of the adjacent plate.

9. In a snap switch of the four-way type, in combination, a shell, snap mechanism in said shell having a non-circular lug oscillated thereby, a thin rigid contact disc loosely mounted on said lug for oscillation thereby in its own plane, two pairs of stationary contacts, those of each pair straddling the disc in opposing relationship and engaging the faces of the same to guide the isc in its movement, bridging contacts on the disc to individually connect together the contacts of each pair when the disc is in one posiadjacent both end walls, a contact carrying plate Y tion and to connect together the contacts o1' separate pairs on the same side of the disc in another position thereof, said disc being of such extent that both pairs of stationary contacts always engage the same.

10. In a snap switch, in combination, a casing of rectangular cross section, snap mechanism in said casing and offset to one side thereof, a bridging contact carrying disc actuated by said mechanism and at the other side of the casing, a terminal plate extending across each end of the casing with its axis substantially parallel to the axis of oscillationof the disc, terminal screws in portions of the plates closer together than the digrooves and a closure for the rear of the shell engaging the rearmost terminal of each pair to hold the pairs in the shell.

12. In a snap switch, in combination, a shell of insulating material open at its rear for the insertion of a switch mechanism and having a front wall, side walls and end walls, said side walls being grooved from the back toward the front of the shell adjacent an end of the shell, a pair of terminal plates insulated from each other and supported from the groovesV adjacent said end wall, contacts associated with the terminal plates and extending in the shell for cooperation with the switch mechanism, terminals available through said end wall and a rear cover plate for said shell and holding the terminal plates in position.

13. In a snap switch, a shell having side walls and an open back and having in its side walls, adjacent to an end thereof, a pair of confronting grooves extending forwardly from the open back of the shell, and contact support means insertable into and positioned by said grooves comprising respective forward and rearward terminals insulated from each other, the adjacent end 'of the shell being cut away to give wiring access to said terminals.'

VICTOR R. DESPARD. MARK N. RUSSELL. 

